This invention relates to radio communications and more specifically to radio frequency (RF) mixer circuit and method used in RF equipment.
RF communication equipment generally uses mixers to convert a signal from a low frequency to a high frequency or a high frequency to a low frequency by mixing the signal with a local oscillator (LO) signal. The LO frequency can be above or below the frequency of a desired signal to produce a sum and a difference frequency, one of which is the frequency of interest.
Mixer performance is critical to the overall performance of the transmit and receive channels of RF equipment that employ mixers. It is especially critical in receiver applications where the dynamic range of the receiver is limited by the mixer. Mixers should have good linearity or intermodulation performance characteristics, wide dynamic range, low power consumption, low noise interference, and offer conversion gain in some applications.
What is needed for direct conversion and other receiver applications is a mixer having little or no anomalous low frequency spurs, low distortion, significantly reduced power consumption, lower noise figure, good balance, and low cost.